Outlet Tee and Standpipe Repair for Grease Interceptors

The inlet fitting brings wastewater into the first chamber and the outlet tee pulls water out of the last one. Mesa's code is the most specific Valley text on the shape of both. The inlet is a 90 degree elbow with a down spout of at least 18 inches. The outlet is a tee with a threaded cover and a down spout of at least 18 inches. The down spouts matter because they reach below the floating grease. Water that leaves through a pipe that starts well under the grease cap leaves cleaner.

A standpipe does a similar job in a different shape. The precast industry's guidelines show a baffle system and a standpipe system side by side and say both use the same principles. In a standpipe tank, a vertical pipe controls where water leaves, and the guidelines use the elevation of that pipe or baffle to work out how much grease the tank can hold before it needs cleaning.

These are small parts in a harsh place, and they fail in a few predictable ways.

• The outlet tee is missing. The pipe now draws from wherever the opening sits, and floating grease can leave with the water.
• The down spout is cracked, short or has dropped off. The fitting is there, but it no longer reaches below the grease.
• The threaded cover is stripped or gone. Mesa lists the cover as part of the outlet build, so an open or missing one is an inspection issue on top of the performance issue.
• A standpipe extension is missing. Capacity worked out from the standpipe's height no longer matches the tank.
• The elbow at the inlet is cracked. Incoming water churns the surface instead of entering below it.

Phoenix's FOG manual says inspectors check for missing parts and write a requirement to repair or replace with a deadline. A missing tee is the sort of finding that appears on that paperwork.

A licensed hauler pumps the tank first, because nobody can see or reach these fittings under a foot of grease and water. Our three-person crew then enters under a confined-space procedure, which is covered on our confined-space entry page. The crew checks the fitting's seat and the pipe it joins, looks for the cause of the failure, and installs the replacement.

The matching matters. Phoenix's amendment says gravity interceptors are installed per the manufacturer's instructions, and the city's approved list requires engineered, certified designs. So a replacement tee should follow what the tank maker drew, and in Mesa it must also meet the 18 inch down spout and the threaded cover. We ask for the tank's make and size when you call, because it saves a second trip for the right part.

Afterward we write down which fitting failed, what we installed and what the rest of the tank looked like. That goes in your log. Chandler's record list includes the nature of service, and Phoenix wants repairs on file for three years.

A missing tee or standpipe extension can make a well-kept tank behave like a neglected one. If you have been pumping more often to chase grease in the lateral, the fitting may be the real cause. See grease in the sewer line after an interceptor for how to sort it out, and what happens when a baffle or tee breaks for what the codes say.

Once the fitting is back, the schedule can go back to what the grease load calls for. Phoenix's manual says a new facility should adjust its pumping frequency to the amount of grease actually accumulated.

If the fitting failed because the surrounding wall is rotted, a new tee will not hold in a bad wall. We will tell you that when we see it, and the answer becomes grease interceptor replacement. If the damage is to the wall between chambers, that is a baffle repair. If the tank is simply full, you need a pump-out, not a repair.

You can also check one thing yourself. Ask your pumper to tell you before they leave if a tee or elbow looks loose, cracked or gone, and to take a photo. Phoenix suggests operators witness every cleaning for this reason.

Tell us your city, the tank size and what the pumper or inspector said. We offer 24/7 emergency service, free estimates, and an upfront price before work starts. For the pump-out side, see pump-out and repair coordination. Related services are grease trap service and restaurant plumbing.